"Secretary Mattis is currently visiting with troops at Guantanamo Bay for the holidays to thank them for their service," Pentagon spokesman COL Rob Manning told CNN.

The Associated Press accompanied Mattis and was first to report on his trip. Defense Department Spokesperson Sue Gough also confirmed the secretary's travel to CNN on Thursday.

Multiple officials told CNN that Mattis was there only to visit troops and not to discuss detainee policy or inspect detention facilities.

Guantanamo Bay Naval Station, or "Gitmo," has been the center of political controversy for several years. Former President Barack Obama announced intentions to close the detention center when he was first elected, however, it still remains open and President Donald Trump has endorsed the continued, and perhaps expanded, use of the facility.

In November, Trump suggested sending the suspect of a deadly terror attack in New York City there to be held.

"Send him to Gitmo. I would certainly consider that," Trump said at a Cabinet meeting at the time. "We need quick justice and we need strong justice -- much quicker and much stronger than we have right now. Because what we have right now is a joke, and it's a laughingstock."

Following the attack in New York, Attorney General Jeff Sessions also raised the possibility.

"Terrorists should know: This administration will use all lawful tools at our disposal, including prosecution in Article III courts and at Guantanamo Bay," Sessions' prepared speech said. "If anyone has any doubt about that, they can ask the more than 500 criminals whom the Department of Justice has convicted of terrorism-related offenses since 9/11. And they can ask the dozens of enemy combatants in Guantanamo Bay."

Mattis is not the first Trump administration official to visit Gitmo, Sessions visited the site in July 2017, along with his deputy, Rod Rosenstein and Director of National Intelligence Dan Coats.